How does PHP interact with the drop-down list? Solution

How does PHP interact with the drop-down list? For example, I have a table with two fields: name. a drop-down list of the class reads all the data of the class from the database, and a drop-down list reads all the names of the classes. How to do this ?, Use ajax to retrieve data. js/jquery to update page content or read all data at a time to write PHP. how does one implement linkage of the drop-down list?
For example, I have a table with two fields: name. a drop-down list of the class reads all the data of the class from the database.


Output all names. How can this be done?

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Use ajax to retrieve data. js/jquery to update page content
Or read all the data and write it to the page at a time.
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I always think there is a problem with your table design.
Is this name the name of the class or the name of the student ???
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Drop-down menu
Onchange event

Then use ajax to request the server
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What does this have to do with PHP? Search for links by yourself, with a bunch of code
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It is not suitable for students and classes to be placed in a table.
Student table: sid, sname, classid
Class table: classid, classname

The first drop-down menu reads the class table,
Ajax is used for association. when the data in the first drop-down menu is changed and an event is triggered, student table is selected based on the classid and all name values are listed in the second menu.

I don't know what name is. The above is just a general description. if you have any questions, you can just take a look.
Hey.